6mm Stainless Steel Anticorrosion Miniature Linear Slide Bush, It is seals on both sides, NB SMS5G 5mm Slide Bush Ball Miniature Linear Motion Bearings, The retainer material is resin, SMS6GUU-P bearing is a Precision accuracy grade Miniature linear bushings, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan.